WE can't get enough of our ancestors. And we've taken to tracing them in cyberspace, if the multitude of family history websites is anything to go by.

With 100,000 sites dedicated to genealogy - only porn attracts more hits - the internet has become a prime tool to trace the family tree.

The publication for the first time on the internet of the 1901 census for England on Wales is guaranteed to spark even more interest in our roots. The site was inundated with so many hits during its first three hours it virtually ground to a halt.

The Edwardian census will be the largest genealogical record on the Web. It has 3.25m names, and lists addresses, employment and state of mental health.

Genealogical research was largely an antiquarian and upper-middle-class interest until the 1950s.

That's when it really took off, says Sue Gibbons, librarian at the Society of Genealogists. ''People from much less exalted walks of life started doing research into the history of their families no matter if they were butchers, bakers and candlestick makers,'' she says.

Before the internet, genealogists trawled through parish records, went to St Catherine's House in London for birth, marriage and death certificates and the Public Records Office, also in the capital, for the census.

The internet has spawned a mass of sites dedicated to genealogy. Perhaps most fruitful are name groups, sites for researching the ancestry of a particular name.

THE family search site maintained by Mormons lists over two billion transcripts of baptisms and marriages. You can also see indexes of birth, marriages and death certificates online.

Telephone directories from all over the world are also published online, which allow you to contact people abroad you suspect might be related. Ms Gibbons says the internet has opened up family research to those who otherwise didn't have the time.

She says: ''It has enabled mothers at home with children to research their family trees and the census will make an enormous difference.''

But searching for information about predecessors can be fraught with difficulties. Gleaning information from the census may not be that easy.

''Success depends on what kind of family class you come from. Upper class families tend to appear in all sorts of records,'' Ms Gibbons says.

''Enumerators were meant to go down every street in the country but they may have been too frightened to go down some of the roughest areas.

''If you were in a back street slum the census enumerator may have been too frightened to go down there.

''And some people may not have given them the right information. Or they just fled. If they can't pay their rent for example they might have piled all their belongings in a wheelbarrow and left when they knew about the census.''

For people with foreign ancestry research can also be harder because names often change over the years.

High levels of illiteracy in Edwardian times also meant names were corrupted.

If women had an illegitimate child, they would often refuse to identify the father.

Many people had reasons for not wanting to be on the census, says Ms Gibbons. ''In London, all you had to do was cross the river and no one would know who you were. You could set-up family with another wife and the last thing you wanted was your name recorded,'' says Ms Gibbons.

When research does reap results, that can be a mixed blessing.

''You will always find people who discover things they wish they hadn't,'' says Ms Gibbons.

''Illegitimacy used to be scandalous but that doesn't upset people any more. But finding that an ancestor was really unpleasant, perhaps convicted of something like gang-rape, or that someone who was thought to be a mother was in fact a grandmother, that is really upsetting.

''Other people can be surprised when they find they are related to a lord, even though they have been brought-up on a council estate,'' she says.

ALTHOUGH a lot of research can be done at home, it's a mistake to think you can find out all you want without leaving your computer terminal.

Whatever you find on the internet should be checked with the original records because anything typed on to the computer could have been misspelt.

Family historian Jeanne Bunting says: ''Tremendous strides have been made with the internet. It has brought about a new breed of historian.

''But it's a big mistake is to think you can do everything on the computer at home. It's a mistake to think you will find your family tree back to Adam and Eve by pressing a few buttons.''

Here are a few internet sites that could help in the search:

sog.org.uk UK society of Genealogists website, offering guidance on how to research family history

census.pro.gov.uk Public Record Office 1901 census

familysearch.org Site maintained by Mormons

cyndislist.com 95,500 links to genealogical resources on the internet

freebmd.rootsweb.com indexes birth marriage and death certificates