I just wrote the following sentence:
… there might have been interesting reasons for as to why they did.
My question concerns the passage "reasons for as to why". While this sounds perfectly right to my non-native speaker self, I wonder whether it includes just too man prepositions and whether "reasons as to why" would also do the trick. Any ideas about the difference between "reasons (for) as to why" and about which one ought to be preferred?
(By the way: google search provides hundreds of thousands example for both.)