It’s both, but I would think that experiences have a bigger influence, and you could argue that they help to make us who were are. But then again, I believe that God plans out my life, so perhaps He shapes me. But if He shapes me, why aren’t I a better person? Perhaps all our experiences in this life affect us in the next life.
I think of the Apostle Paul. He was zealous for God before he became a believer in Jesus, but he persecuted the church. He later described himself as the chief of sinners. But then, after his conversion, he became a huge influence for good. And in Scripture, you often see God allowing bad things to happen with a good end in view. The supreme example of that is the crucifixion of Jesus. In Acts 4, a prayer of the early church is recorded that makes references to that:
Acts 4:27-28
27 Indeed Herod and Pontius Pilate met together with the Gentiles and the people of Israel in this city to conspire against your holy servant Jesus, whom you anointed. 28 They did what your power and will had decided beforehand should happen.
The church drew comfort from the fact that God knows what He’s doing – even if we don’t.
Here are a couple of hymns about God’s purposes for us:
Hibernia Gospel 