My sister is a young millennial in her late 20s and lives at home with our mom. They live in Los Angeles. My sister will likely NEVER be able to afford to buy a house in Los Angeles, and there is no sense in paying rent when our mom is happy for the company.

My mom is an immigrant, and she has always welcomed her adult children to live with her (even to the point of insistence). I fully expect to go live with her when she reaches her elderly years. I'm even kind of looking forward to it. I live across the country from my whole family and this has been a very isolating experience, even if it was my choice to do so.

I don't think it is weird for adults to live with their family. I actually think it's weirder and more unnatural NOT to live near or close to your family.