@Kevin1855 You don't seem to have a rule on your listing that you only host guests over the age of 25.
Airbnb says that you are not allowed to discriminate based on age, unless there's a rule in place at your property's location that says that people have to be a certain age to rent. For example, I used to have a cottage in a resort: the resort rules stated that we couldn't rent to anyone under the age of 25, so I could get away with stating no rentals to anyone under 25. If it was just a personal preference, a guest could have reported me to Airbnb for discrimination.
And to answer your initial question: no, Airbnb will not verify the age of your guest.