N-FETs behaving strangely when connected in parallel
In your simulation you are using an idealized FET model. There is no leakage across the source to drain and so the voltage divider stays unloaded and produces the 1V like you expect. 

When you apply a real FET that does have leakage it loads the divider to cause the divider to produce a lower voltage. Excessive leakage will make the divider output approach zero.

After all with the resistor values shown the current through the unloaded divider is only ~10uA. 

Your BSS170 is speced in its data sheet to have a MAX leakage is 0.5uA with zero gate voltage. So if your two FETs were good you could expect to see a little bit of droop of the 1V from the divider. 

Have you been careful in handling your FETs? Devices like the BSS170 have very high gate impedance and can be damaged simply in handling if there is static electricity build up on your body from clothing or carpet or padded chair. I suspect that one of your FETs may be damaged.