I'd say cousins, since Jesus is a prophet but Muhammad (peace and blessing upon both) is the final prophet. That and Islam is largely (from what I have learned thus far) more about improving yourself as a person and as a Muslim than repenting or asking for forgiveness from sin. You do ask for forgiveness, but if you are a strong believer, if you keep Islam firm in your heart, and you follow the rules as well as doing good deeds, then you will enjoy the best in akhirat (hereafter). I still have allot to learn and change, which happens slowly. Allah knows that if Islam banned alcohol right away, people would ignore it. Thus Islam must be taught and weaved slowly, so you learn why it should be banned and then have time to change.

I’d say half siblings.