Behavior (US) / Behaviour(UK) is a noun. And yes, in your paragraph you can or should use "Behavioral / Behavioural"

In this context you would only say behavior (It is an adjective) and not behavioral (which is an adverb). Custom has not commonly been regarded as a subject of any great interest. We feel that the inner workings of our brains are uniquely worthy of investigation, however, in terms of custom, we have a certain way of thinking, that our behaviour is very ordinary. Please, when you say custom do you mean tradition, habit or routine ? I have made some corrections but it would depend on what you are trying to convey :) You woulde use behavioral in the folliwng way; There are certain behavioral techniques that you can teach to children that are very helpful. We often think our tradtions are part of us, but often our behavior is something we choose to do. Behaviorally, your students are better than my students. The types of behaviours we see here everyday are not common in other cities.

In this context you would only say behavior (It is an adjective) and not behavioral (which is an adverb). Custom has not commonly been regarded as a subject of any great interest. We feel that the inner workings of our brains are uniquely worthy of investigation, however, in terms of custom, we have a certain way of thinking, that our behaviour is very ordinary. You woulde use behavioral in the folliwng way; There are certain behavioral techniques that you can teach to children that are helpful. We often think our tradtions are part of us, but often our behaviour is something we choose to do. Behaviourally your students are better than my students. The types of behaviours we see here everyday are not common in other cities. When you say custom do you mean tradition, habit routine? I have made some corrections but it would depend on what you are trying to convey :)