+118723 Humans have 46 chromosomes in every cell of the body (except s***m and ova)
One of those is responsible for determining the s*x of the person. This is the s*x chromosome.
Chromosomes come in pairs. So there are 23 pairs of chromosomes.
For males, just one chromosome is shorter than the others, but the other in the pair is normal length. For females they are both normal legth.
The male s***m dertermines the s*x of the child. If it ends up with the long chromosome (called X) of this pair the child will be a girl. If the s***m ends up with the short one (called a Y chromosome) then the child will be a boy.
http://www.biology4kids.com/files/cell_chromosome.html
https://www.youtube.com/watch?v=xUrlreMaUrs
