These are some facts I found about Ferb:

1. He was adopted by Phineas's parents despite the resemblance of him and Phineas's father.

2. He showed Phineas how to build as baby's.

3. The only time (Ive ever found him) laugh was when he and Phineas made a toy doll house for Candace.

and 4. The most lines he has ever had during a show was 7.