Alex's Answer

Physical changes happen to me when I see my sister change her clothes

Your Question

I am living with my sister in the same room. I’m 9 and my sister is 13. We are changing clothes in front of each other often. I noticed my Willy became too big and too hard, it feels warm and sensitive when she changes her underwear. Is it normal or I need to visit the doctor


Hi there, you’re very welcome to Ask Alex. Thanks for trusting us with your thoughts today. 

You mentioned you are living in the same room as your sister, and you change clothes in front of each other. You said you noticed a physical change in your penis when she changes her underwear and you’re wondering if this is normal or if you should visit the doctor.  

Firstly, thank you for sharing what’s going on for you. It’s not always easy to talk about these things so well done for reaching out. Secondly, as we get older, it’s normal for changes to happen in our body. It sounds like you are going through what is known as puberty. This is the process of developing from a child into an adult. The average age for boys to start puberty is 12 years old but it’s normal to begin at any point between 9 and 14. When we feel changes in our body like you mentioned for the first time, it can feel strange and it’s understandable that you might feel worried. Just know that you’re going through significant developments at the moment both physically and mentally so it’s normal to feel a mix of different emotions. 

Sometimes talking can help too. Is there anyone in your life that you would be comfortable chatting to about this, like an older sibling, relative or maybe a friend? You do have the right to share your feelings with somebody that you trust. If you’re not ready to talk yet and want to find out more information, you might find this video on our Childline website useful: It talks a bit about what puberty is. You can check out more facts here too: 

If you feel more comfortable talking to someone outside the family, it might be easier to reach out to Childline. We’re here 24 hours a day through web chat at, by texting 50101 or you could give us a call on 1800 66 66 66.  These services are open every day and are free and confidential. We will listen to your thoughts and feelings without judgment and help explore some options that may be available to you.  

We hope you found some of this information helpful. Remember we in Childline are always here to listen to what you have to say.  

Take care of yourself. We hope to hear from you soon,   


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