"I don't think that for my black son, growing up in Britain, celebrating a White Christmas is really appropriate. Traditional Christmas celebrations are essentially Eurocentric - Santa Claus, Christmas trees, reindeers," she says.
"I think it's important to have festivities which are self- affirming and relevant to our culture. I had problems when I was growing up coming to terms with my heritage - I used to want straight, long hair like my friends. I want my son to feel good about himself in a white-dominated society. Although I was brought up in a Christian family, I'm not religious now, so Christmas isn't particularly important," she says.
The festival which celebrates black cultural pride and encourages qualities such as black unity, self-determination and co-operation is becoming increasingly popular among Britain's black people.
On each day of the Kwanzaa holiday, which runs from Boxing Day to 2 January, a member of the Williams family will light a red candle symbolising African blood shed in the struggle for freedom or a green candle representing fertility and hope. They will reflect on the seven principles of Kwanzaa: unity, self-determination, collective work and responsibility, co- operative economics, purpose, creativity and faith. During the last day, a lavish meal will be served with a variety of foods from different cultures.
Recognised by millions around the world, Kwanzaa was created by a Los Angeles-based black activist, Maulana Karenga, in 1966 as part of the black pride movement.
Ajani Bandele-Mason, who observes Kwanzaa with his family, has this year sold hundreds of Kwanzaa cards from his shop, Timbuktu Books and Culture, in Brixton, south London. It is the first time he has seen Kwanzaa cards outsell Christmas cards. "I think the growth of Kwanzaa here since the 1980s, is indicative of increased black consciousness. I went to the Kwanzaa event at the African-Caribbean Cultural Centre in north London last year and it was packed - it was the biggest attendance I'd ever seen at an African event."
This year there are nine leading Kwanzaa events in Britain. Many families will dress in traditional African clothes for the festivals, which will be marked with speeches and music.
Ronald Nathan, director of the African-Caribbean Evangelical Alliance, says: "Kwanzaa is not a substitute for Christmas. For me it is an addition to my celebrations over the birth of Jesus Christ. There is a pressing need for us to reinforce our culturalvalue system. Our slave history has led to the corruption of our traditional positive African value system. There are children in the world who will kill to buy some trainers, becaus e fashion is more important than a life.
"Kwanzaa is reviving our cultural heritage and giving us a spiritual and moral basis to bring us out of the poverty trap and problems such as drugs and violence."
While the majority of black people still celebrate Christmas, Mr Bandele-Mason says many introduce a cultural component: "They may send friends cards depicting a black Father Christmas or black Bible figures and send African-inspired gifts."
Generally, there is also greater awareness of the need to cater for a more culturally conscious community.
For example, this year the American civil rights leader the Rev Jesse Jackson, criticises world leaders for a failure to tackle racism and injustice in a speech being screened at the same time as the Queen's Christmas message.