My daughter's father has schizophrenia. My daughter has a speech delay, poor eye contact, and so on. Should she have an evaluation? And is there anything we can do to ward off the illness?
Yes, your daughter should have an evaluation for speech delay and poor eye contact, and whatever other symptoms she may have that interfere with her function. A psychiatric consultation and neuropsychological evaluation in particular are indicated.
I don´t know the age of your daughter, but I presume she is still in school, and effective communication is important for success there, and in other domains of her life. With an evaluation, your daughter can obtain therapy and remediation for her current symptoms, and may be able to obtain accommodation in classes and in test-taking as needed.
As for her risk of schizophrenia, it is about 15% based on her father having schizophrenia, though her having symptoms may increase this risk somewhat. Despite her family history and symptoms, she may not be at appreciable risk for schizophrenia (so remember it is not a foregone conclusion). Given that, your best course for prevention is to obtain evaluation and treatment for her current difficulties, focus on her strengths, protect her self-esteem, foster good coping and stress management, and encourage your daughter to stay away from drugs such as marijuana.
I am sorry that there is not more that I can offer you and your daughter in terms of reducing her risk for schizophrenia, but I can assure you that we are busily working on this very issue.