I would imagine that being straight probably describes the largest segment of the population. As far as what's "normal" or not when it comes to swinging or having multiple partners, it's all much too subjective to make any such determination. I think the answer lies in what YOU think of those things. Do YOU like swinging or not? Do YOU get jealous?
Perhaps the questions might be better asked if I were to change the "YOU" to "YOUR PARTNER"?