Based on prior knowledge, we can assume that the age group for a person can be categorized into "Adult" or "Senior". To analyze the relationship between the feature "RIAGENDR" (Gender) and the target variable, we can examine the typical values of "RIAGENDR" for each age group.

Here is the dictionary with the required format:

```json
{
    "Adult": [1.0, 1.0, 2.0, 2.0, 2.0],
    "Senior": [1.0, 2.0, 1.0, 1.0, 2.0]
}
```

In the above dictionary, the "Adult" category represents people of working age, while the "Senior" category represents elderly individuals. The values of the "RIAGENDR" feature (Gender) are presented as floats in the lists. From the provided data, five typical values for each age group are included. Please note that the specific values may vary depending on the dataset used.