Is it required to have a family member co-sign a lease for an apartment when you are old enough to get an apartment by yourself or can someone you trust co-sign?

No, it is not required to have a family member co-sign a lease; anyone you trust can act as a co-signer, provided they meet the landlord's criteria. The co-signer typically needs to have good credit and sufficient income to support the lease obligations. Landlords often allow flexibility regarding who can co-sign, as long as they are willing to take on the financial responsibility.