I don't love my brother. Is that bad?

Love . Love is preferable but not always possible. Sometimes family relationships can be improved over time with forgiveness, new experiences, maturity. If you're concerned about this you might want to speak with a therapist. They often have tips for mending relationships that can be mended and accepting those that cannot.
Sibling Love. Many of us have complicated relationships with our siblings. Maybe the more relevant question is how did it come about that you don't feel love for your brother and can whaterver conflict you have be resolved between you. Empathy is the key to postive relationships, ask yourself if you are making an attempt to understand his point of view. Best.