noun
Refers to one's own child or descendant, often with a nuance of lineage or bloodline. Somewhat formal or literary.
彼は自分の子種に財産を残した。
He left his fortune to his offspring.
noun
Euphemistic or literary term for sperm; often used in contexts of procreation or lineage. Compare with the more clinical 精子 (せいし).
See also: 精子
子種がなければ子は生まれない。
Without seed, no child can be born.
精子 is the standard biological/medical term for sperm, while 子種 is a more literary or euphemistic expression often tied to lineage.
Compound of 子 (child) and 種 (seed). The exact historical derivation is uncertain, but the combination naturally yields the meanings 'offspring' and 'sperm/seed'.