Is this possible? 10-day-old new-born baby of heavy metal singer flashes Rock 'n' Roll sign

Popular Japanese heavy metal singer Nao Hazuki shared the photo on the right claiming his new born daughter flipped the sign at just 10 days old. The photo has since gone viral with many believing it's photo shop. But the new dad, who fronts the Japanese heavy-metal band Grollschwert, claim it's not. What do you guys think? Is this possible?