That does explain a lot. Ahsoka takes a deep breath and lets it out slowly, there's a hint of pain, but also love to make her feelings bittersweet.

"I heard Anakin had a son, but hadn't gotten around to asking anyone about it. It's true, Anakin Skywalker was my Jedi Master for three standard years during the Clone Wars." She glances over at Luke and gives him a small smile. "He is more than just my Master, I consider him to be my brother. It hurts, what happened to him, but whatever you want to talk about, I'm willing."

Ahsoka wanted to share stories of Anakin with Obi-Wan before he found out what happened, but that may be a long time off. So if Luke wants to know - she will do her best to tell him everything. Perhaps it's telling, that she still calls him family, that Ahsoka sees him as more than just Darth Vader.