After Anakin Solo died, Han Solo & Leia gave birth to Ben Solo to replace his loss. But when he found out he was a "replacement child" instead of "something original", he must have mistook it for being adopted & something went teribbly wrong with his mind, which led him to join the First Order with Jaina (whom he later might have disposed of out of loss for interest), then slain Lando Calrissian, Jacen Solo, & then revive him for the price of possessing him, (similar to Xehanort possessing Terra), thus, turning them into Kylo Ren.
After Anakin Solo died, Han Solo & Leia gave birth to Ben Solo to replace his loss. But when he found out he was a "replacement child" instead of "something original", he must have mistook it for being adopted & something went teribbly wrong with his mind, which led him to join the First Order with Jaina (whom he later might have disposed of out of loss for interest), then slain Lando Calrissian, Jacen Solo, & then revive him for the price of possessing him, (similar to Xehanort possessing Terra), thus, turning them into Kylo Ren.