it has a huge things to do with genetics. I noticed the quality I get from one line that came from one of the top Mini Lop
breeders...pretty much throws me a big butt and a perfect crown. They have been line bred properly, so the trait has almost been set it stone for the most part. The buck of course, has a gorgeous, correct head & crown. When bred to a doe with a slightly tighter crown, it corrects itself with the offspring.
When I breed with one of my bucks with a tighter crown, he tends to throw me exactly that, but he throws me wider,thicker babies.
Thus, I'll be correcting those offspring with the other buck.
I tried line breeding my tighter crown buck back to his daughter and it was probably one of the worst litters I ever had. I had intensified the moderately tight crown...they had slipped crowns....airplaine ears..... Never again! A whole litter of culls
With the buck that throws correct crowns, my babies are lopping sometimes as early as day one. The ears will already ever so slightly be flopping forward and finally by 2 weeks, they will be flopping even more so and are usually completely flopped by 3 weeks.
so breeding wise, if you want to improve upon it, find yourself a buck with a loose crown that hangs loosely just behind the eye. I haven't been able to improve my crowns ever unless one parent or the other had the desirable crown and ear.