Look at the birds. Nobody tells them to migrate at a certain time of the year they just do it because instinct tells them to do it. Instinct tells a baby buck to get up within the first few few seconds after birth and hide from predators. The mother don't teach him that, he knows that instinctively
Natural instinct means an instinct which comes naturally. Take for example : A virgo is too Adventurous, it is a natural instinct loll