??? Healthtap is a good source of medical information when used as designed. To get the most out of HT. Please describe an issue, provide enough background for review, and ask a specific question. Your question is offered without any specific details, so at best we can say anyone "could" be dyslexic. You are welcome to start over with specific info. Questions are not linked.
Talk to professional. Not sure if your brother is teasing you or serious, but dyslexia is generally best made by a professional (doctor, psychologist), and often based on special testing (neurocognitive). Talk with your doctor as the place to start if you're concerned.