Christmas and Saturnalia

My question is wether christmas has anything to do with the roman holidays? I know this is a vividly debated topic, and I saw many different opinions. Some say christmas and a lot of tradition comes from the roman festivals Saturnalia or Sol Invictus, but others say it is just a coincidence, because the choice of the date has other causes and christmas was already celebrated before 313 A. D. What is the truth, and what is your opinions on this case? Thank you for your insights.