How much DNA did you inherit from your mother and father? If you guessed 50% from each parent... well, you’re only half right. While women do inherit 50% of their DNA from each parent, men inherit about 51% from their mother and only 49% from their father.

For all you men out there, is this proof you really are a mama’s boy? Why the discrepancy?

To answer this question, first a little 101 in genetics: all humans, both male and female, inherit 23 chromosome pairs from their parents, for a total of 46 chromosomes. Half of each pairing comes from an individual’s mother and half from the father. In 22 of these chromosome pairings (known as “autosomes”), each half of the pairing is roughly the same length and size.

A 23rd chromosome pairing consists of two “allosomes,” more commonly known as “sex chromosomes.” Sex chromosomes can either be an X or Y. Unlike the 22 autosomes, X and Y chromosomes are NOT the same size.

The sex chromosome pairing for a man is XY, meaning all you fellas out there inherited one X from your mother and one Y from your father. Women, on the other hand, have a sex chromosome pairing of XX, inheriting one X chromosome from each parent.

The Y chromosome found in males is about one-third the size of an X chromosome—and contains significantly less DNA. An X chromosome has HUNDREDS more genes than a Y chromosome. It’s this discrepancy in the size of X and Y chromosomes that accounts for why men inherit 51% of their DNA from their mothers and only 49% from their fathers.

With a Gene Heritage Parent-Child Report, you can see which genes have been passed down from a parent to a child.

As a side note, mitochondrial DNA is passed down exclusively along the maternal line (from mothers to children), but only accounts for a piddling 0.0003% of your DNA . Still, it’s just a bit more proof that women have a leg up on all you men out there. But does size really matter?