Q For Seed Planters

[rangerdanger]

At another cultivation website someone posted that they can sex their plants from seed at 3 weeks old. Not by light manipulation, just vegging.
Sounds fishy to me.
Can anyone here determine the sex of plants at 3 weeks old?

[Heath_Bogenreif]

Most indica based strains will show preflowers between 8-12 nodes. If youre not there in 3 weeks you should be there no later than four.