I have required 2 baby female guinea pigs, they where in a litter of 4 girls. I have been told that they are 10 weeks old. Now I have 2 boys that are 8 weeks old and they weigh .550g and 520g. The girls weigh .292g and .300g at 10 weeks old. The boys weighed the same as the girls at 4 weeks old. I know that boys are bigger but do you think the girls are younger then 10 weeks?