Loudmouth,
You ask,
Explain how post-fertilization activities affect allele distribution.
What you mean, I guess, is allele frequency. So, parents who don't divorce, who love each other increasingly over the course of their marriage, especially post-fertilization, enhance the psychological well-being of their offspring, who respond by having more grand-children. Evolution would look for genes that enhance such behavior. Creation would look for evidence that the Creator was pleased, and would then artificially select, and genetically engineer changes in response to a couple's choosing this life-style. In the present context, such genes are probably already present, but suppressed by demons, and all the Creator has to do in response to the parental choice and prayer for protection, is "deliver them from the evil one."
How do you explain infertility among creationists? Sorry, not buying this one.
Case by case, we normally have to ask Jehovah. But, clearly, there is more to getting the blessing of fertility from God than just believing in creation. There's the prayer aspect, as well. Do a Google on prayer and fertility. But, believing in creation is a part, and it ought to be statistically correlated with some blessing. Other variables create an error term, statistically.
What about the idea makes you not want to buy it?
Stephen