A question

[bertstare]

A white woman marries a black man.They have four children-2 sons and 2 daughters.What proportion of these children is likely to be black.

1-25%
2-50%
3-100%
4-none


Answer in the science General Knowledge book is 4.I want the explanation for this.

[JackBean]

what is 4.1? None and 25%?

To my knowledge the skin color is not sex determined, thus, if we assume they parents are not mixed already, we should expect 50% (although it will be rather that all four children will be slightly black)

[javedshaikm]

As per my knowledge - let us assume
1) white woman(WWbb - gamete ) marries Black man (BBww - gamete)
then first generation would be(in normal case) -

White Daughter (WWBw) + White son (WwBw)

or

White Daughter (WWBw) + black son (BwBw)

So the percentage would be 25%

[canalon]

Do you really think that skin color in human is a single trait that is present or absent? If so I suggest that you get out of your home and walk on the streets for a few minutes...

[wbla3335]

The question makes the assumption that the woman and the man are purebreds (hard to find these days). Any offspring between the two cannot therefore be purebred white or black (answer 4). As canalon implies, people aren't peas.