Genes
noun
If 遺伝 is heredity and you pass your heredity to your child, how is it being passed? Via genes, of course.
いでんし
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
本当に彼らは父親を鑑定する遺伝子検査を受けたいんでしょうか。
I’m wondering if they really want to get the paternity test done.