Bicep peak is 100% genetic (excluding sytherol). My arms are the exact shape as Lou Ferrigno's. I have done everything to get a peak. My arms get bigger and thicker but the "peak" never changes. Look at guys like Ferrigno, Levrone and Olivia. Those guys have much better genetics than guys like us. However, regardless of their superior genetics, access to better and newer equipment and personal dieticians they still do not have peaks.
Look on the bright side, guys who have longer muscle bellies in the arms have more room for growth. Ferrigno's arms were much bigger than Arnold's and say someone like Larry Scott.
If you don't have a good peak then concentrate on size and vascularity. Also, bring the tri's up. More times than not, the bicep can only be seen when you are intentionally flexing them. Huge triceps will show when you are doing anyting. Just my opinion.