First Time Growing From Seed

So i have grown before but I always had clones and just threw them in and started budding... This is my first time growing from seed. I got some seeds from a friend. Out of 8 only 4 sprouted. Planted them and now i am about 23 days into it, got them in pots under 24 hours of flourecent lighting and they are all only about 6 inches tall... Is this normal???? Should they be a lot bigger? Any ideas????