Cronus is the youngest son of Uranus(Sky) and Gaia(Earth).
Uranus/Gaea/Cronus - Dada asking to kill momma to son
They did have other hideous looking kids like Cyclops and Hecatoncheires.
Uranus hid them in Tartarus,inside Gaia which caused her lot of pain.
And on top of all this, she was getting tired of knocked up game.
Uranus wasnt a seahorse or wasnt ready to borrow the pregancy.
So, in order to take revenge she asked her kids to kill their dad and free her from this non-stop marathon in bed - to make babies followed by popping out those.
Again we are talking about pre-Epidural, pre-spinal, pre-c-section period.
The older sons Titan, Lapetus were not ready to take that offer.
But the youngest Cronus did and Gaia gave him a sickle and laid a trap for Uranus.
When he came near her, Cronus ambushed him and chopped off his genitals and threw them at sea. From his semen many more kids were born.
Here, Mama said "Hurt your daddy" and the son chopped off his dad's privates with the sickle his mama gave him.
Jamadagni/Renuka/Parasuram - Dada said kill your mommy and also siblings
Parasuram is the youngest son of Renuka and Jamadagni.
One day she was to fetch some water for her hubby's ritual, and accidentally she watched one of demigods in action with his wives.
You cant blame the woman, this happened during pre-porn or porn-free, vibrator-free period, she lost track of time.
The enraged hubby who came to know about this by clairvoyance considered it as infidelity and called for his sons.
See, men during that period too never tried to get viagra or anything, instead blamed the wife for infidelity.
He asked his kids to chop their mom's head off.
The older kids refused to kill.
Just then his last son Parasuram came back from one of his quest.
Jamadagni just told him to chop off his mom's head and also his brothers.
Parasuram didnt hesitate and chopped all of their heads.
Here Dada said "Kill your mommy" and the son chooped off his mama's head with his axe.
(Gaea could have switched places with Renuka but see these Greek woman I dont know maybe due to male-female ratio? like this Gaia she is actually the mom of Uranus and then she became his wife and gave birth to Cronus and Rhea and many. And her son Cronus married her daughter ie his sister Rhea- twisted and this never stopped till Roman Caesar and Greek Cleopatra)
Moral of the story: Never bring kids into parent's fight. Parasuram never got married and became a serial killer and his quest all through his life was to kill the men of royality (Kshatriyas). Cronus married his sister Rhea and never trusted his kids and swallowed all his children right after they were born.