def get_fam_size(FamSize, position):
    """
    (dict, int) -> tuple
    
    :param FamSize: A dictionary with family size for each position, and parent umi
    :param position: A given position in a genomic region. 0-based
    
    Returns a tuple with the minimum and mean family size at position
    """
    L = []
    for i in FamSize[position]:
        for j in FamSize[position][i]:
            L.append(FamSize[position][i][j])
    min_fam, mean_fam = min(L), sum(L) / len(L)
    return min_fam, mean_fam
