Which type of make up brush is non-synthetic and the softest?

sable?

squirrel/Grey squirrel?

pony hair?

goat hair?

Which type of make up brush is non-synthetic and the softest?

Pony hair or sable is what I would recommend many people have allergies to goat hair and don't even know it because we do not come in contact often with goat hair!

Which type of make up brush is non-synthetic and the softest?

I was in Sephora the other day looking at brush kits and they had the most wonderful brushes made with goat hair. I would prefer to use them over other ones. :)