Recessive genes

It's a recessive gene.

It's caused by a recessive gene.

You must have the recessive genes in the family.

Well, you share some of the same recessive genes.

Like recessive genes, they sometimes suddenly re-expressthemselves.

The odds are entirely dependant on whether they're dominant or recessive genes controlling the obesity and the dwarfism, which, by the way, is way less offensive than the M word, so...

Although crude and inaccurate, this toy could demonstrate recessive and dominant genes through breeding.