Exactly this. People notice this when they have kids and kids start going to kindergarten.

I was almost never sick with colds until my kid started going out with other kids. I thought I had a great immunity, it happens I only had good hygiene - washing hands, avoiding contact, rarely going to mass event during flu season and etc.

As kids have poorer hygiene habits, are in very very close contact with each other they get sick easier. After a week or so the father is sick with exactly the same symptoms.