I must say I never had a problem with the Toddler Group I used to take DGS2 to every week. The regulars were five grandmothers, perhaps ten mums, one grandad, and two dads. The grandparents did get on very well, but we mixed with most of the younger ones too, and were occasionally asked for advice, which was nice.
And the three men weren't left out at all. We had a lovely couple running it, childminders the same age as me, and we all took turns making the refreshments and clearing up. We paid £1 per child. Afternoons worked for this group, as it finished 10 minutes before the primary school up the road did, which fitted in well with the school pick up.