I'm guessing it has to do with the fact that Chris is working on so many projects all at once and since he needs beard for those Steve gets it too. Red Sea Diving Resort and Jekyll are both in production as well as Infinity War.
At first I thought this was really sweet and about a couple of normal siblings. Then I continued reading and now I'm crying.<<<<<You bitches at first I thought this was some sweet ass thing about to NORMAL siblings, but no. My own damn fandom ruined it