Final answer:
A couple with brown eyes can have a green-eyed child if both parents carry the gene for green eyes. This can occur when both parents are heterozygous for the green trait on the green-blue eye gene, meaning they carry one dominant brown allele and one recessive green allele.
Step-by-step explanation:
In humans, eye color is determined by multiple genes. While it is not mentioned how many genes are involved in this specific scenario, it is possible for a couple with brown eyes to have a green-eyed child if both parents carry the gene for green eyes.
Based on the probabilities given in the question, it is likely that both parents are heterozygous for the green trait on the green-blue eye gene. This means that they both carry one dominant brown allele and one recessive green allele. When these alleles combine in their child, there is a chance that the child will inherit two recessive green alleles, resulting in green eyes.
It is important to note that eye color inheritance can be more complex in reality, with variations in gene expression and other factors involved. The Eye Color Calculator mentioned in the question can be a useful tool to explore these complexities further.