This is just strange, and we find it odd that people even conduct research on such things, but they do, and the numbers apparently don't lie. US President Donald Trump is apparently not a fan of shaking hands - because he finds it unhygienic - but that's apparently something he has in common with millennials. They're more likely to go for a hug than a handshake, if they even want any physical contact with other people at all.
Even when they do shake hands, they do so with little conviction. People used to be judged by how firm their handshake was, and according to the Journal of Hand Therapy, millennials have particularly limp handshakes. Future generations might come to look at the idea of gripping the limb of someone you've just met as hard as you possibly can as a very weird idea.