The essence of the game is that there is no character of your own (in this case customization would make sense). Sexperiment - it's something like a mixture of strategy and sims. Game characters are your units, you can develop, improve and use them in the right situations. At the same time, the characters have their own unique parameters, for example preferable poses, well, in general, every character has his own character. This affects the course of the experiment in general. Your task is to control the process of intercourse characters so that the experiment has come to the desired result.
Yes, maybe now everything is not clear, because the current version does not allow you to try this. But already in the next updates you can see what I'm talking about.