Question

An actress with O type blood accused a producer with B type blood of being the father of her child in a paternity suit. The child was also O type. What does the blood type suggest about his guilt?

Short answer

Based on the given blood types, it is possible for the producer with B type blood (BO alleles) to be the father of the child with O type blood (OO alleles), as the child could inherit an O allele from both parents. However, this blood type analysis alone is not enough to confirm paternity or determine guilt in the paternity suit. Additional evidence, such as a DNA test, would be needed for a definitive conclusion.

Step-by-step solution

Understanding blood types and inheritance

To solve this problem, we first need to understand how blood types are determined by the ABO gene. There are three possible alleles for this gene: A, B, and O. Every individual inherits one allele from each parent, resulting in one of the four blood type combinations: AA or AO (Type A), BB or BO (Type B), AB (Type AB), or OO (Type O).

Determining the blood type alleles of the actress and child

The actress and child both have O type blood, which means they both have two O alleles (OO).

Determining the possible blood type alleles of the producer

The producer has B type blood, so he could have one of two allele combinations: BB or BO.

Analyzing the possible inheritance of blood types

With the possible alleles of the producer (BB or BO) and the known alleles of the actress (OO), we can now analyze if it's possible for the child to inherit the O type blood (OO) from these parents: 1. If the producer has BB alleles, the child could inherit either a B allele from him and an O allele from the actress, resulting in BO blood type, or a B allele from both parents, resulting in BB blood type. In this case, the child cannot have O type blood. 2. If the producer has BO alleles, the child could inherit an O allele from him and an O allele from the actress, resulting in OO blood type (O type). In this case, the child can have O type blood.

Drawing a conclusion based on blood type analysis

From the analysis, we can see that it's possible for a child with O type blood to have a father with B type blood (BO alleles). Therefore, the blood type information does not exclude the producer as the father of the child. However, it's important to note that this analysis alone is not enough to confirm paternity or determine his guilt in the paternity suit. Additional evidence, such as a DNA test, would be needed to establish paternity with certainty.

Key concepts

ABO Gene Alleles

The ABO gene alleles are crucial for determining an individual's blood type, which can be A, B, AB, or O. Each individual inherits one allele (variant) from each parent, combining to form their blood type. There are three different ABO alleles: A, B, and O. The A and B alleles are co-dominant, meaning that if an individual inherits one of each (genotype AB), they will have AB blood type. On the other hand, the O allele is recessive, which means that a person must inherit an O allele from both parents (genotype OO) to have O type blood.

Let's look at the basic combinations. If a person has AA or AO genotype, they will have Type A blood. BB or BO will result in Type B. AB results in Type AB, and only OO will produce Type O blood. This is because the O allele does not code for any antigens on the surface of the red blood cells, while A and B alleles do. The presence or absence of these antigens determines an individual's blood type.

Understanding these genetic mechanisms is pivotal when analyzing family relationships, medical transfusion compatibility, and even in forensic cases.

Genetic Inheritance

Genetic inheritance is the process by which genetic information is passed on from parents to their offspring. It's the biological handover that determines much of an individual's physical and even some behavioral traits. In the context of blood type, this genetic inheritance is a straightforward example of Mendelian genetics, where the alleles from parents combine to give the child their genotype for blood type.

Here's how it works: Each parent provides one allele to their child, and it is the combination of these two alleles that determines the child's blood type. However, because some alleles are dominant over others, the actual blood type (phenotype) of the child might not be a direct representation of the genotype (actual genetic makeup). For example, since O is recessive, a child must inherit an O from both parents to display an O blood type phenotypically. If only one parent contributes an O and the other contributes an A or B, the child will have either A or B blood type respectively due to the dominance of the A and B alleles.

Genetic inheritance patterns explain why certain traits appear in the subsequent generation and can help predict the likelihood of an offspring inheriting a particular trait, which is crucial in the study of genetics and heredity.

Paternity Suit Analysis

Paternity suit analysis generally involves determining whether a man is the biological father of a child. Blood type testing can be a preliminary step in this process. In our scenario, the man has Type B blood which could have the genotypes BB or BO, while the mother and child have Type O, which is OO. The child inheriting OO genotype means the father must have an O to donate; hence, a man with a BO genotype can be the father, while a man with BB cannot.

However, blood type analysis alone is often insufficient for conclusive paternity determination because of the possibility of multiple individuals having the same blood type and potential genotype. That's where DNA testing comes into play, providing a more accurate and definitive analysis. DNA testing evaluates multiple genetic markers and compares the child's DNA profile with the alleged father. The more markers that match, the higher the probability of paternity. In the modern legal context, DNA testing is the gold standard for paternity suits, forensics, and other genetic lineage investigations, replacing blood type analysis due to its precision and reliability.