If they really are that age and have been kept together for that amount of time without any breeding or fighting taking place then I would guess they are all female, but sexing them is the only way to be sure. It may cost you but IMO it would be fairer to house them separately.
1.0.0 Dumerils Boa (Khan)
1.1.0 Corns (Snow Coral Motley 'Jonesy' & Carolina het Am,An,Hyp,Mot 'Indy')
0.0.2 Crested Gecko (Billy The Kid & Jesse James)
0.1.0 Bearded Dragon (Missy)
1.0.0 Leopard Gecko (Derick)
0.1.0 Homo sapiens (Nicole)