parvathy params

I just wishbto know that in this serial how come the kid of the eldest couple , that is naina's tauji and taiji's child is the youngest of the cousins and the youngest brother that is naina's chachaji's kids are the oldest. The daughter of the chacha Chachi is old enough to get married and that tauji's son pralay is just 7 or 8 years old. Pls koi batao