If they are living in YOUR house.........They are a guest. I cant even believe they thought for a second that they had any right to tell you not to get chickens in the first place. The nerve people have!!!!
(and being allergic to birds is a real allergy but the symptoms they describe don't really mesh up. Even horses can have bird allergies so my coup is not in my horse barn .. just to be safe.)
Threaten Pigs next usually stops all complaints on Chickens
A farmer a few miles away got 5 hens and a roo - the neighbors called the police every time the rooster crowed he sold the chickens got pigs they make no noise but no one for 3 miles can sit outside the smell is so bad --bet they wish for a roo to crow --
My DH and son are both allergic to our chickens. They get the typical stuffed/runny nose and lots and lots of sneezing. Plus their asthma acts up making it literally difficult to breathe. It only flared up when the chicks were young and still in the house. We had to move the chicks to the basement until their coop was finished as my guys asthma and allergies got very bad. Thankfully they don't mind having them here at all as long as the chickens are outside.
I do agree that since it's your place and your inlaws are renting from you ... they can make a (single) comment and then they need to find something else to do with their lives or move.
My MIL actually wants pigs LOL but we are not zoned for them. She also asked why I need a rooster because I can hatch eggs without one and what will I do with the chickens when they hatch because nobody will want them. All I could say to that was !!!!!!!WHAT!!!!!!!!!!!! This is from someone who grew up around chickens. I am not kidding her mom raised chickens her whole life, you would think she would know a little bit about them. I sure don't want to have the chicken sex talk with her so I let that one go LOL