You know, gods and titans and all that don't have to actually have sex with a human to make them pregnant. Chronos could as well have shot an energy, part of himself through the prison of hell, through some opening and that energy wandered the world for the perfect vessel. Once it found the mother, it made her pregnant and BAM you have the child of Chronos.
"The war between the Gods was causing anomalies  all around the world. The barrier which divided hell from earth was breaking, cracks had begun to show. And from those cracks, Father Time took the opportunity to expel some of his energy which contained himself in it, to the realm of earthlings."

"Before the Titan of Time, Chronos was imprisoned by his son Zeus, he expelled a part of himself in the form of energy. This energy disappeared as it vanished from the current timeline. It traveled through countless ages and timelines until it found the right moment to emerge and find a vessel. The vessel would give birth to a child of Chronos. As foreseen and planned by Chronos when he was imprisoned, this child would then later help him escape from the prison. This was assured as he imprinted a part of himself in that child and with that his own will."

There are countless version from which you can pick to pull this off. Be creative!