do you think it's normal??? 😳

So my sister in law is much older than me she has 5 kids the oldest one is 30 and the youngest 25.... I started to notice that when ever one of her sons sits next to her she grabs his nipple or whenever he's near her and today she was "discreetly" trying to rub his crack 😨 in my viewing it's not normal and makes me uncomfortable it's none of my business I know.... I don't see this normal at all