Jean Johnson may be an agent but the answer is wrong. The correct one is:
The duplex that you occupy will qualify for an FHA loan. The other 3 duplexes that you purchase will qualify as investment properties and will require a larger down payment (about 20%) + higher interest rates + higher fees.
Lenders are able to give low interest rates, low fees and low down payments ONLY to occupied residential properties (you need to live in it for 12 months). If you don't occupy a residence, it is considered an investment property and requires a higher down payment, higher fees and higher interest rates.