Imho, it’ partly because then they know their kids have reached that stage in their lives where they are stable and have a home as well as are socially cared for and care for their significant other. Puts their minds at ease basically and they can age peacefully. Most parents basically want the best for their children and this is one symptom of it (now I’m prepared to get the replies of all the people with shitty parents.)

Maul on the bowl

They both look like avocados to me