Honestly, it may not be as personal as it seems. I would ask your friends(cousins?).
One of my best friends messaged me one day and told me she blocked me on facebook because I posted snake pictures all the time. It's not that she thinks they're gross or slimy. She's terrified of snakes and has a real phobia of them. I totally forgot about her phobia and apparently she freaked out every time she saw a snake on her computer screen.
I eventually just blocked her from seeing that particular snake album and she unblocked me. All is well.
Tell him that the common family dog has a higher chance of attacking a child.
I don't have the exact statistics, but something like 20 children die each year from dog attacks. The humane society states that pet snakes have been responsible for only 12 deaths in the US in the last 30 years. (These were larger breed snakes that were most likely not housed correctly too)