Considering that life on a 4d planet would have more space to live in it might reproduce at a faster rate. Cells in 4d might divide into three cells when splitting as one way to speed up reproduction. They might also have a triple helix instead of a double helix of a DNA analog in order for this to happen.
Also in 4d organisms that would use sexual reproduction to reproduce would probably need to join together in groups of three or even four in order to reproduce. Some would probably have three or four chromosome pears and so cross over of genes might involve three or four chromosomes. A zygote might split into nine or twelve gametes.
Some species would probably also have three or four genders. For three gendered species they could potentially have every gender completely unique or have one gender a complete mixture of the other two or have one a mixture of the other two but with its own traits as well. For species with four genders there might be so to speak two dimensions of gender. They might have the malemale, malefemale femalmale, and the femalefemale for example with each gender having two sets of gender related traits. I wander though what might be some of the ways a 4d organisms gender would be determined if 4d species were to have more than two genders.