You have problems with letting people in
This is not your ex talking, so try not to drift back into memories of tearful car rides punctuated by awkward silences. No. What I mean is that jiu-jitsu posture can be counter intuitive. One of the first concepts we talk about with new students is the idea of keeping your elbows in and tight. I used to call it Home Alone hands, but stopped when my younger students started admitting that they have never seen or heard of that movie. Now I steal the Eddie Bravo nomenclature and describe this position as “t-rex arms.”
Regardless of the terms, holding your arms close may be safer in the jiu-jitsu sense, but it requires you to let your opponent within make-out range. Instead, your instinct is to hold your arms straight. Distance feels safe. The farther away your problem is, the less threatened you feel. One armbar will tell you that your instinct to protect your personal space is not sufficient for jiu-jitsu, but the instinct remains difficult to squelch nonetheless.
Rise above your programming
You are more than your genetics. You are equipped with a complex learning machine that will allow you to adopt new behaviors and new habits if you are willing to endure a few growing pains. You will try, and you will fail, but you will eventually succeed. Failing is a part of learning.
The mat is the most honest source of feedback that you will ever have. You will know when you have made a mistake. If you can become mindful, you can identify the predispositions and habits and tendencies that work against your jiu-jitsu goals. Some of these habits may be rooted in centuries of evolution and others may be a product of your lifestyle. In the end, however, you are in control of the computer that drives your jiu-jitsu.