Rig Veda X.78.6 says that Maruts are sons of Sindhu.
These noble sons of Sindhu are like grinding-stones, they are always like Soma-stones , tearing everything to pieces; these sons of a good mother are like playful children, they are by their glare like a great troop on its march.
Rig Veda 6.66.3 says that Maruts are the sons of Pṛśni.
They who are Sons of the rain-pouring Rudra, whom the long-lasting One had power to foster: The Mighty Ones whose germ great Mother Pṛśni is known to have received for man's advantage.
Can anyone explain reason for this?