"Real life" doesn't even remotely resemble the ancestral environment. In the modern world, a big family is evidence about your cultural background, especially the relationship between your cultural background and contraception, and that might be a turn-off for some. This is the same kind of phenomenon that makes having extra fat evidence, in the ancestral environment, that you were good at acquiring food and other resources, but in the modern world it's evidence that you're poor or lack access to good food or lack self-control or whatever.