I assume phobias come natural in most of cases. I think it might have come natural from when humans first started as the snakes and spiders would be venomous and dangerous so avoiding them at all costs was something regularly done. I could be wrong but it sounds reasonable.

Others have had bad experiences which cause their phobias, which is understandable.

I love both snakes and spiders, although I hate big flying bugs, like the palverde beatles that are coming out. Saw two of them last night, ugghh. Have you ever had a big black bumblebee land on you?