You are the child of L, you were taken along with him to Japan when he chose to work on the Kira case, L was working with the task force and you walked in, staring to the members and then your gaze fell on Light Yagami, before looking away.

Soichiro Yagami (Light's father) then spoke "who is this? L, why do you have a child with you." Everyone then turned to look to L and he simply looked to you.