Logically everything which exists now must have had a beginning. In actuality, this might not be true for everything, but it's difficult for a finite human mind to genuinely grok a beginningless anything, so let's dismiss this possibility for the purposes of this train of thought.
A thing that is, such as myself, cannot reasonably understand a universe without itself. This means it's difficult (if not impossible) to honestly grasp your own genesis. We can look at others, observe their beginning, and extrapolate that understanding upon ourselves, but this is an intellectual exercise without the tangibility of true first-hand knowledge.