But for the thousands of teenagers throughout the UK who can't live with their birth families, these difficult behaviours can be the mask in front of the hurt that is only exacerbated by having no place to call home. That's why a stable, loving foster home can make the world of difference.
Carla was taken into foster care at the age of 12, but - in her own words - she began to display challenging behaviours, especially at school.
Carla says: "One day when I was at school I stood defiantly in front of the head teacher and lit a cigarette. He was telling me to put it out. I just kept saying why, who are you going to tell? I don't live with my mum and my social worker doesn't care. I don't have anyone you can tell."
Within a year Carla had been to seven different foster families, and social services were struggling to find anywhere for her to live. Her previous behaviours and various placement breakdowns meant she was destined for a residential placement which wouldn't have met her needs, until she met the Randalls.
Carla continues: "My most poignant memory of being in care is probably the first day I went to the Randalls' house. I compared the house to a palace and I literally jumped up and down when no one was looking. I even had my own room. I can remember exactly what everyone was wearing, my foster mum's smile and what we had for dinner.
"My foster mum was kind and she knew I was scared. That night she came into my bedroom in the middle of the night where I lay on top of the bed awake and reassured me that I could get under the covers and make myself comfortable. From then on it wasn't all rainbows and smiles, it took a lot of hard work and understanding on their part to make me feel secure and trust that things would work out."
Carla received lots of support and stability, and with the help of her foster carers she moved schools and was encouraged to work hard to get her GCSEs. Carla received extra tuition and support to catch up on the school work she had missed out on over the years. She then studied social work at the University of East Anglia, and whilst at university, Carla frequently returned to the Randalls'.
When she finished there was no question about where she was going to live - like most of her friends, she went home to her foster family. She also started working in a residential children's home.
"I got to work with children that were like I used to be. Full of attitude, mixing with the wrong crowds, displaying challenging behaviour. It was a great experience for me, I just wanted to help them, show them that there is a different path.
"Looking back now I realised that the Randalls saved my life. I never understood the extent of the neglect and abuse I had endured until I came to live with a 'normal' loving family. They nurtured a young, angry, untrusting teenager to become a positive, empathetic and successful young woman."
Today Carla works for a fostering agency called Little Acorns Fostering, and she gives back to the system that, in the end, helped her move forward as an individual.
Sadly Carla's early time within the care system doesn't make her a unique case. Two in five (40%) fostered teenagers are already living with their third foster family since coming into care, and one in twenty (5%) are on at least their tenth family in care.
Stability affects us all, and when you have none you feel alone. Children in foster care are our children, and as a member of a fair and good society we have a duty to do all we can to make them feel loved and supported. They deserve a positive future as much as any child and at The Fostering Network we're determined to help them achieve that.
Good foster care changes lives, it saves lives, and it develops lives. I know that many reading this article won't have the life situation where they can foster, but if you have a spare room, are over 18, and have love and the passion and dedication to learn new skills - then come forward and find out if you could help someone like Carla build a life that they can be proud of. Visit fostering.net to find your local fostering service.
Everyone knows teenagers. They're the ones who need love and stability.