Any genetics games that get really technical?

You might have better luck searching for genetics or population genetics simulators than for creature-breeding games. A simulator may let you focus on inheritance and gene interactions without building the experience around raising animals or surviving. The tradeoff is that it may feel more like a learning tool than a game.

When comparing options, check whether they explain the inheritance rules and let you inspect genotypes, rather than showing only visible traits. It may also help to decide whether you want individual organisms, family pedigrees, or whole populations. Those are different kinds of genetics problems, so narrowing that down could make recommendations more relevant.