The Y chromosome is passed on by the father.
Understanding Sex Chromosomes
To understand how the Y chromosome is passed down, it's important to know a bit about sex chromosomes. Humans typically have 23 pairs of chromosomes, for a total of 46, with one chromosome in each pair inherited from each parent. One of those pairs are the sex chromosomes, which determine if an individual is genetically male or female.
- Females have two X chromosomes (XX).
- Males have one X chromosome and one Y chromosome (XY).
How the Y Chromosome is Inherited
According to the reference: "Females always pass an X chromosome onto their offspring. If the father passes on an X chromosome, the baby will be genetically female, and if the father passes on a Y chromosome, the baby will be genetically male."
Here’s a breakdown of how sex is determined by chromosome inheritance:
| Parent | Chromosome contribution | Child's Chromosome | Child's Sex |
|---|---|---|---|
| Mother (XX) | Always an X | ||
| Father (XY) | X or Y | X from mother + X from father = XX | Female |
| Father (XY) | X or Y | X from mother + Y from father = XY | Male |
Therefore, the Y chromosome can only be passed down from a father to his son. The Y chromosome does not exist in mothers, who have two X chromosomes (XX). This makes the father the sole contributor of the Y chromosome in offspring.
