Like his father, he has brown eyes. Unlike his siblings who both only favor one parent, Farkle looks like both, having Fiona's hair and Shrek's facial features.
Shrek the Third
Fiona brings up the idea of Shrek and her starting a family. Shrek quickly dismisses it, pointing out that babies are a lot of work. As Shrek is leaving for his journey to get Artie, Fiona reveals to Shrek that she is pregnant. Shrek is shocked and has nightmares of being a father, not being able to protect them from various hazards. His relationship with his own abusive father causes him to worry that he will be the same kind of father he had. At the end of the film Fiona gives birth to them and appeared in the credits along with Donkey and Puss.
Shrek the Halls
Shrek Forever After