Life of Pi
OK. There's no sex in Life of Pi. Pi has other concerns. Like survival, for instance. Before his family leaves Tamil Nadu, Pi thinks about little else but zoology and religion. Of course, the animals aren't quite as pure of mind as Pi. They can definitely get a little feisty:
"A natural transition, you might think, from hotelkeeping to zookeeping. Not so. In many ways, running a zoo is a hotelkeeper's worst nightmare. [...]. To speak frankly, many [guests] are sexual deviants, either terribly repressed and subject to explosions of frenzied lasciviousness or openly depraved, in either case regularly affronting management with gross outrages of free sex and incest." (1.4.3)
There are also the onanists who "sweat" on the monkeys (1.8.2). But that's it. Nature shows are usually good, clean fun. PG is the highest we'd go here – and only then because Pi compares animals to depraved hotel guests. Even Victorian novels are steamier than Life of Pi.