There are a lot of very right wing and socially conservative people in the SNP.
47% of the party voted for Katie Forbes in the leadership election, an out and out bigot.
But they're the main party pushing for Scottish independence, so I'd guess plenty will have joined just for that, especially when momentum was on their side.
That and the fact that they were the overwhelming party of governance when plenty of current MPs and MSPs came in.
Now independence doesn't seem to be a realistic possibility in the short term, there'll be fragmentation.