Everyone knows it's hard to breed giant pandas in captivity - to the point where it's easy to wonder how they survive in the wild. Showing them pornography has been tried.
Now it turns out? Pandas, unlike many animals, won't just get it on when you stick them in with a "genetically approved" mate. In fact, there is absolutely no chance of a cub unless the pair like each other.
...which, of course, throws all of the breeding programs into a tizzy. And how many other animals does this apply to? It certainly applies to some species of bird. Arranged marriages in zebra finches drop the survival rate of chicks by over a third and increase rates of infidelity.
How much does it apply to humans? Humans have sex with people they aren't particularly attracted to all of the time, but does it affect how many children are produced? A lot of studies have been done about marriage length, relationship stability and "love" in arranged marriages versus love matches, but I'm not able to find anything that addresses reproductive success, probably because cultures that still arrange marriages also tend to have less availability of pre-natal care and contraception (short intervals between pregnancies can also affect infant mortality).