I imagine massive amounts of malnutrition and the inability to settle in non-temperate regions. Without meat or dairy products, you'd need a way to get a food surplus for long winters when plants have given up. It is possible to get complete protein from plant products, but these plants aren't native to most of the world. You also wouldn't have animal products like cat gut or hide.

Unless cows are monsters. In which case I could see a few hilarious incidents where people stab new beings. If they reincarnate, then they're probably sentient. And they forget that you stabbed them!

Through if people's biological impulses go wonky, I imagine trying to murder someone undesirable to get a baby would actually occur. I mean, you kill a few rapists and some people get to adopt a baby. Or if they have no biological impulse to take care of a baby, they are suddenly cursed with the presence of a screaming, wailing poop fiend. Which would probably not end well.