Final answer:
Adverse responses from the sibling to a new infant can include aggression, withdrawal, or regression in behavior, often due to feelings of jealousy or the stress of adjusted family roles. It's crucial to provide support to prevent such adverse reactions and promote a healthy family dynamic.
Step-by-step explanation:
Adverse responses from the sibling to a new infant can include a range of behaviors, potentially rooted in jealousy, anxiety about the changes in family dynamics, or the stress of adjusting to a new role within the family unit. These adverse responses might manifest as acts of aggression towards the infant, withdrawal from family interactions, or even the mimicking of infantile behavior as a plea for attention. Particularly in cases where older siblings take on a 'parentified' role due to family circumstances like divorce or other care arrangements, they may struggle with their own emotional needs while assuming responsibilities beyond their age. It's important to monitor and support siblings during the transition of welcoming a new infant to help prevent adverse reactions and ensure the mental and emotional well-being of all children involved.