In 1938, the vicar of the parish church at Hucknall Torkard led a party of five or six men into the vaults to open the coffin of Lord Byron. Although a friend had declared his body almost unrecognisable shortly after his death in 1824, more than a century on his latter-day admirers reported that he remained "extraordinarily handsome", that "the slightly protruding lower lip and curly hair were easily recognisable" - and even that his penis showed signs of "quite abnormal development".

This striking scene forms the closing image of Fiona MacCarthy's celebrated Byron: Life and Legend, published in 2002. The context makes it clear she is also thinking about the strange things biographers sometimes do to the dead they admire or envy. MacCarthy has already warned of the "literary wishful thinkers, male biographers of Byron who portrayed their subject according to the image they wished to appropriate for themselves". Perhaps, she seems to be implying, women make better, because more detached, biographers of certain men.

There is also, of course, an opposite view: that cross-gender empathy will always have its limits, because men will never understand what it's like to miscarry and women can't really imagine the humiliation of impotence. This has sometimes been turned into a argument that gender or race or sexual orientation represent insuperable barriers that people ought not to try to surmount.

So what do leading academic biographers have to say, both about the general issue and their own experiences of crossing the gender divide?

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For Frances Spalding, professor of art history at Newcastle University, who has written lives of the critic Roger Fry and the artists Duncan Grant and John Minton (as well as works on several women), "the notion that certain subjects should be barred to certain people is abhorrent".

Instead, she argues, "biographers and novelists must try to go where they do not belong. One of the tasks of a biographer is to open up experience about an individual and the context in which he or she lived, to try and get inside a period, place, class, race, sexual or religious orientation, all possibly very different to one's own. No biography is definitive and all may have inadequacies in places, but we can listen attentively to the accounts of others' experience of miscarriage or impotence. If this is done with emotional intelligence and careful attention to facts, it can break down barriers and enlarge tolerance and understanding."

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Miranda Seymour takes a similar line. A novelist and biographer of Mary Shelley, Robert Graves, Henry James and her father George Fitzroy Seymour, she was also professor of English studies at Nottingham Trent University for much of the last decade and still serves on the board of the Arts and Humanities Research Council-funded Challenges to Biography research network, which is based at the University of Southampton.

"I don't feel that women bring a different quality to writing," she argues. "I think that we bring our own gifts - that's all. I am not comfortable with the idea of gender biography, although I do recognise that the necessary push for female equality led to a certain style of writing that is now very much of its time. The best biographies are written with the sensibility of a fiction writer - and fiction writers, as we know, can write about either sex with equal empathy and confidence.

"I want the freedom to write about men or women with equal ease. Nobody ever said I shouldn't write The Bugatti Queen: In Search of a Motor-racing Legend (2004, about Hell¨¦ Nice) because I was female and thus unlikely to write with competence about a car engine. And if I, who have no knowledge of engineering, can do that, and even get congratulated for my accuracy, I don't see why a man can't write just as well as a woman about the birth of a child.

"The family of Robert Graves asked me to write his biography (published as Robert Graves: Life on the Edge in 1995) because they thought that a woman would bring a different attitude to the problematic area of the 'Muses'," says Seymour, referring to the series of much younger women Graves used obsessively as sources of poetic inspiration.

"I was lucky to benefit from that view, but I didn't, and don't, agree with it. There are plenty of things that occupy my mind when I'm considering a new subject. Gender isn't now, and never has been, one of them."

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John Guy operates from the other side of the divide. A Fellow of Clare College, Cambridge, he has, since 2002, devoted most of his time and energy to biographies such as My Heart Is My Own: A Life of Mary Queen of Scots (2004) and A Daughter's Love: Thomas and Margaret More (2008), the last of whom he describes as "a very savvy 16th-century woman whose father wanted her educated, but not too far, and who blazed a trail for women to enter public life".

His approach, explains Guy, is never to say: "'I'm going to write a biography of a woman and I've got to get inside her head'. Instead, I get hold of a big package of issues and use an individual figure as a tool to unlock a lot of secrets, and I make them accessible by telling a good story.

"Henry VIII, a hugely powerful monarch, was followed by a little boy and two women. People at the time, and even the senior councillors, regarded Mary Tudor and Elizabeth as perpetual minors, because they were women. There was a continual struggle going on behind the scenes for even a royal woman to assert her power. Elizabeth's chief adviser, William Cecil, tried to drive a wedge between her and Mary Queen of Scots, so I use that as a central tool to re-examine the second half of the 16th century. I situate the biography within a heavy-duty model of the nitty-gritty politics of the British Isles."

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Guy acknowledges that there are "gynaecological moments" to be tackled in such a work, and that perhaps first-hand experience of a being a woman in a man's world would offer female biographers a certain advantage, but he emphasises: "That isn't going to stop me. I operate on the principle that nobody can do everything. You've got your take, someone else has got theirs - it's open country here."

It is left to Jane Ridley, professor of history at the University of Buckingham, to put the case that women can bring interestingly different, and perhaps more illuminating, perspectives to charting the lives of certain men.

She refuses to accept what she calls "the Lady Macbeth hypothesis", that "women biographers writing about men must 'unsex' themselves in order to deal with such exclusively male experiences as killing people in war or impotence.

"My approach differs from that of male biographers. I give more emphasis to the role of women and family in the lives of men. My biography of Lutyens (The Architect and His Wife: A Life of Edwin Lutyens, published in 2002) put his marriage at the centre of the story, drawing on the vast correspondence between him and his wife. I was well aware that this approach was very different from the line that a conventional (male) architectural historian would have taken, but it enabled me to make new connections between the life and the work.

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"Of course there are limits to the extent to which a woman can empathise with a man's life, but this is more than outweighed by the advantages. Figures such as the political adventurer Benjamin Disraeli or Edward VII, the philandering prince, tend to attract male biographers who either suppress their rackety lives or glamorise them. As a woman I am more detached, and I hope that I can combine sympathy with salty scepticism."