Lone child syndrome, often known as only child syndrome, is a speculative idea rather than a real syndrome. According to this concept, the only child is a spoiled child as they’re used to getting anything they desire from their parents, including their undivided attention.
This theory states that these kinds of children will grow into selfish individuals who only focus on themselves and their own requirements. Besides, lack of interaction with a sibling is believed to bring about loneliness and antisocial tendencies.