Can a brother seek guardianship of minor 14 year old sister

Thanks for your question.
You would need to hire an attorney to file a Petition to Appoint Guardian.
The court will determine what is in the best interest of your sister.
They will look your income,living arrangements, maturity level and your general ability to raise a child.
Your question did not state whether you were married or if you have other children-certainly something the court will look at.
An attorney can help you with a plan to help convince the court that it would be in the best interest of your sister for you to be appointed the guardian. The court could appoint a guardian of the person and a different custodian of the financial assets.

Under Florida law, you may seek guardianship if you are 18 years or older and have no felony convictions. Please be aware that your sister's parents, if they have no felony convictions would have priority. If they are not alive, they have abandoned your sister or would willingly release to you by signing a consent, then the court would likely favor you provided her grandparents or her other siblings do not seek guardianship of her also.

When we consider guardianship of a minor we look at two sides of the individual, the person (their residence, medical and social circumstances) and their property (finances). Guardianship of a minor first defaults to the natural guardians (the parents). If the parents are unable to continue or, if the person receives certain amounts of monies, then the court may need to appoint a guardian. According to Florida law, family members have first priority in appointment but this is not a guarantee. The judge considers several things in appointing a guardian. Guardianship is a confusing area and minor guardianship is even moreso. Not only will it be helpful to have an attorney, but Florida law requires that an attorney be involved in a guardianship proceeding. It is best to find one that practices in guardianship and is familiar with the court in your sister's county.