In the ansys help manual, there is a general recommendation for the initial amount of samples to use. This quantity must be higher than the total number of input parameters that are active. Ten times the total number of permitted input parameters is the minimum suggested number of first samples. Your odds of locating the input parameter space containing the best solutions increase with the size of the initial sample set.
For more information on using MOGA optimization, have a look at these links.
Multi-Objective Genetic Algorithm (MOGA) (ansys.com)
Performing a MOGA Optimization (ansys.com)
Thanks and Regards,
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