Kartikeya's birth is described through various legends in Hindu mythology, with common elements across texts:

• Shiva and Parvati are his parents. The birth was necessitated to defeat the demon Tarakasura, who had a boon that only Shiva's son could kill him.
• One legend states that during Shiva and Parvati's union, Shiva's seed (semen) was inadvertently spilled. This seed was too potent for any one deity to sustain. It was passed from Agni (the fire god) to Ganga (the river goddess), who deposited it in the Himalayas or in the Ganges river.
• From this divine energy or seed, six sparks or babies emerged, nurtured by six celestial mothers called the Krittikas (Pleiades). Parvati later fused these six into one child with six faces, hence Kartikeya also known as Shanmukha (six-faced).
• Kartikeya was thus born with six heads and multiple arms, symbolizing his power and divine origin. He was raised by the Krittikas and grew rapidly into a mighty warrior.
• This divine birth story signifies Kartikeya as the combined offspring of Shiva, Parvati, Agni, Ganga, and the Krittikas, created specifically to lead the gods' army against the demon Tarakasura.
• Some texts add that Kamadeva (god of love) was sent to awaken Shiva from meditation to enable this birth, and that Kartikeya was born on the sixth day (Sasthi) of the lunar month Margashirsha.

In summary, Kartikeya was born from Shiva's divine seed, incubated and nurtured by Agni, Ganga, and the six Krittikas, and then unified by Parvati into a powerful six-headed god destined to defeat evil