2 plants 1 1/2 months old, no sex...?

SO unfortunately out of my six beauties, 2 are male.
1 is a definate Female,
But the other three are undecided. (I meant three in my title.)
Is this normal?
Also, I don't think it matters but the plants are as healthy as can be.

It can take while for plants to show there sex. 1.5 months is nothing to be too worried about. If you still cant tell within a few weeks something funky might be going on. Are they all the same strain? if so, then they should sex at similar times. If you have some pics that would be awesome. A lot of people on this site are great at identifying males and females.